Brain and Neurologic Function: Several types of brain lesions are seen in individuals with tuberous sclerosis complex (TSC); some people will have all the lesions, whereas others will have no brain involvement at all.

Cortical tubers (from which TSC is named) can be thought of as a "birth defect" on the brain. They are small areas in the cortex (the outer layer of the brain) that do not develop normally. It is thought that the presence of cortical tubers, which disrupts the normal "wiring" of the brain, is what causes seizures in individuals with TSC.

Subependymal nodules develop near the walls of the cerebral ventricles (the cavities in the brain that contain cerebrospinal fluid). Typically, these nodules accumulate calcium within the first few months or years of life. Because of this calcification, they can be easily detected with a computed tomography (CT) scan. The subependymal nodules are not directly responsible for neurological problems.

Subependymal giant cell astrocytomas (SEGAs). This type of tumor develops in approximately 15 percent of individuals with tuberous sclerosis. Typically, SEGAs do not occur in very young children, and the chance for their growth decreases after age 20.

If a giant cell astrocytoma grows large enough, it can block the flow of fluid inside the ventricles of the brain, and the tumor will have to be removed and/or the ventricles shunted to relieve fluid buildup and pressure. Symptoms include vomiting, nausea, and headaches as well as changes in appetite, behavior, and mood. These symptoms may or may not signal growth of a tumor, but they do signify that there may be a problem and that the child should be seen by a physician.

Brain imaging should be done at the time of diagnosis to get a baseline image and then every 1 to 3 years afterward. A brain scan can sometimes show growth of a tumor even before symptoms develop.

The most common affect of brain manifestation is epilepsy or seizures. Seizures occur in approximately 85 percent of individuals diagnosed with TSC.